Ordered as HB90178, this is an AS568-178 black Buna-N (Nitrile) 90 Shore A Back-Up Ring built to an inside diameter of 9.737 in (247.32 mm), a cross section of 0.103 in (2.62 mm), and an outside diameter of 9.943 in (252.55 mm). The back-up ring extends o-ring service life by supporting the seal against extrusion under high pressure.
Buna-N (Nitrile) is specified here for economical choice for high-volume maintenance programs and low compression set under sustained load. The compound resists greases and lubricants, hydraulic fluids, and many alcohols. Service temperature is rated from -40°F (-40°C) through 250°F (121.1°C).
Typical settings include hydraulic and pneumatic systems, construction equipment, and automotive.
Order part number HB90178, sold individually. Nominal inside diameter is listed as 9 3/4 inch. Check the compound against your process media, pressure and temperature before committing to a design.
Description 8-178 BLACK BUNA 90D BACK-UP RING
Actual Cross Section 0.103 inch (2.62 mm)
Actual Inside Diameter 9.737 inch (247.32 mm)
Actual Outside Diameter 9.943 inch (252.55 mm)
Measurement System Imperial
Product Category O-Rings - Backup Rings